Footage taken from the Syrian city of Qamishli just across the border showed tanks, which are believed to be from the Turkish military, firing rounds as they moved into position.

Footage taken from the Syrian city of Qamishli just across the border showed tanks, which are believed to be from the Turkish military, firing rounds as they moved into position.

Bulldozers were also visible as they demolished buildings in the urban settlement, while there are large plumes of thick black smoke rising into the air. The constant sound of shelling can also be heard.

Violent clashes between the Turkish armed forces and Kurdish separatists have led to numerous deaths on both sides over the last few days. On Friday, Turkish Kurdish fighters reportedly blew up an armored vehicle and damaged a tank, while a day earlier Turkish artillery hit a neighborhood in Nusaybin.

Ankara's operation against the Kurdistan Workers Party (PKK) began in July 2015, breaking a two-year ceasefire between the two sides and reigniting a conflict that has killed more than 40,000 people since 1984.

European leaders and international human rights groups have fiercely criticized the operation. On Friday, the UN said they would send a mission to Turkey to investigate alleged human rights abuses in the country's mainly Kurdish southeast.

"We are ready to send a team at the earliest opportunity and, in light of the statement by the [Turkish] Ministry of Foreign Affairs, look forward to swift official confirmation that this mission will indeed be welcomed and fully supported by the Turkish authorities," Rupert Colville, a spokesman for the Office of the United Nations High Commissioner for Human Rights (OHCHR), said at a briefing in Geneva.

Colville went on to state that “full and unhindered access for the UN human rights team to the affected population and locations, authorities, documentation and other relevant materials in southeast Turkey is essential for any credible fact-finding exercise."

In particular, the UN said it wanted to investigate reports that more than 100 people were burned to death in the town of Cizre while sheltering in basements surrounded by Turkish forces, following a special report by RT from the settlement.

UN Human Rights Chief Zeid Ra’ad Al Hussein said that to have such a “lack of information” about what is happening in the region is both “extraordinary” and “deeply worrying,” and “fuels suspicions about what has been going on.”

It comes just three days after the UN urged Turkey to allow investigators to probe allegations of abuse by security forces in the campaign against the PKK.

The Kurdish militants are fighting for the right to self-determination and greater autonomy for Kurds – demands that have been rejected by Turkey.

As of early April, almost 400 soldiers and police and several thousand militants had been killed since the conflict was restarted in July 2015. Opposition parties said at the time that between 500 and 1,000 civilians had also been killed in the fighting.